7.5 cm KwK 40

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7.5 cm KwK 40/L48 on a Panzer IV.

The 7.5 cm KwK 40 (7.5 cm Kampfwagenkanone 40) was a German 7.5 cm Second World War era vehicle mounted gun, used as the primary weapon of the German Panzer IV (F2 models onwards) medium tank and the Sturmgeschütz III and Sturmgeschütz IV assault guns (F models onwards).

The KwK was adapted from the similar towed anti-tank gun, the 7.5 cm Pak 40. It replaced the short-barrel 7.5 cm KwK 37 L/24 close-support gun, providing a huge improvement in firepower for mid-war tank designs. It came in two versions, with L/43 and L/48 barrel lengths, the former used during 1942 and early 1943, and the latter after that point. Along with the Pak 40, the KwK 40/StuK 40 was the most numerous anti-tank gun of the German army.

History

When mounted on a casemate-armored assault gun-designated vehicle (Sturmpanzer) instead of a turreted tank, the weapon was called Sturmkanone 40 (StuK 40). Both the KwK 40 and StuK 40 was developed from the towed 7.5 cm Pak 40 anti-tank gun. Ammunition was shortened in length to allow easy storage for KwK 40 and StuK 40.

The L/43 version was mounted on the Panzer IV from April 1942 until June 1943. All 225 vehicles of the Panzer IV F2 mounted the L/43 version with a ball shaped muzzle brake. About thousand out of 1687 vehicles of the Panzer IV Ausf. G mounted the L/43 with a double baffle muzzle brake. The StuG III with the L/43 gun was designated as Ausf. F. of which only 120 were equipped with the L/43 version (the remaining 246 having the longer L/48 version). All Ausf. F/8 and G of StuG III mounted the longer L/48. The 780 original Jagdpanzer IV mounted the PaK 39 variant of the L/48 gun, the later Panzer IV/70 mounted the StuK 42 L/70.

The L/48 was 334 mm (13.1 inches) longer and slightly more powerful than the L/43. L/48 became the standard gun from June 1942 until the end of World War II. The gun was fitted with an electric firing mechanism and the breech operated semi-automatically. Only one-piece ammunition was used.

  • Following number of vehicles mounted L/48 version from June 1942-April 1945
    • Approximately 6,000 vehicles of Ausf. G, H, J out of 8,800 Panzer IV
    • 7,720 vehicles of StuG III Ausf. G + 246 of Ausf.F + 250 vehicles of StuG III Ausf. F/8
    • All 1,139 vehicles of StuG IV
    • 780 Jagdpanzer IV

As with the 7.5 cm Pak 40, the muzzle brake of the KwK 40 and StuK 40 went through a series of design changes. Five types of muzzle brakes were used, gradually increasing the area of exposure to the blast. The designs progressed from tubular type double baffle muzzle brakes to single baffle ball shape muzzle brakes, which proved to be insufficient in reducing recoil, followed by a double flange type from May 1943. The front flange and rear disk type was used from March 1944, followed finally by the double disc type.

Ammunition

Gun maintenance on a Sturmgeschütz III.

KwK 40 used shell 75×495 mm. R [1]

  • Pzgr. Patr. 39 KwK 40 (Armour Piercing Capped Ballistic Cap (APCBC) High Explosive round)
    • Muzzle velocity: 790 m/s
    • Projectile: Panzergranate 39 (Pzgr. 39)
    • Projectile weight: 6.80 kg
    • Explosive filler: 18 g of RDX/wax
    • Fuze: BdZ 5103 or BdZ 5103* base fuze
    • Round weight: 11.52 kg
    • Cartridge case height: 495 mm
    • Propelling charge: 2.410 kg of Digl. R.P. G1
    • Primer: electric, model C/22 or C/22 St.
  • Pzgr. Patr. 40 KwK 40 (Armour Piercing Composite Rigid)
    • Muzzle velocity: 990 m/s
    • Projectile: Panzergranate 40
    • Projectile weight: 4.10 kg
    • Explosive filler: none
    • Fuze: none
    • Round weight: 8.61 kg
    • Cartridge case height: 495 mm
    • Propelling charge: 2.2 kg of Gu. R.P. 7,7
    • Primer: electric, model C/22 or C/22 St.
  • Gr. Patr. 38 HL/B KwK 40 (High Explosive Anti-Tank)
    • Muzzle velocity: 475 m/s
    • Projectile: Gr. 38 HL/B
    • Projectile weight: 4.60 kg
    • Explosive filler: 0.51 kg of RDX/wax
    • Fuze: A.Z. 38 St
    • Round weight: 7.36 kg
    • Cartridge case height: 495 mm
    • Propelling charge: 0.43 kg of Gu. Bl. P.-AO
    • Primer: electric, model C/22 or C/22 St.
  • 7.5 cm Sprgr.Patr.34 KwK 40 (High Explosive) L/48
    • Muzzle velocity: 550 m/s
    • Projectile: Sprgr. 34
    • Projectile weight: 5.75 kg
    • Explosive filler: 0.66 kg of amatol
    • Fuze: kl. A.Z. 23 (0,15) umg. nose fuze
    • Round weight: 8.71 kg
    • Cartridge case height: 495 mm
    • Propelling charge: 0.755 kg of Gu. Bl. P.-AO
    • Primer: electric, model C/22 or C/22 St.

Penetration comparison

Penetration in mm, armor plate inclined at 30 degrees from vertical[2]
Gun type Barrel length
(mm)		 Ammunition type Muzzle velocity
(m/s)		 Penetration (mm)
100 m 500 m 1000 m 1500 m 2000 m
7.5 cm KwK 37 L/24 1766.5 mm K.Gr.Patr.rot.Pz 385 m/s (1,260 ft/s) 41 39 35 33 30
7.5 cm StuK 40 L/43 3281   mm Pzgr.Ptr.39 740 m/s (2,400 ft/s) 99 91 82 72 63
7.5 cm KwK 40 L/48 3615   mm Pzgr.Ptr.39 790 m/s (2,600 ft/s) 110 97 86 75 64
7.5 cm KwK 40 L/48 3615   mm Pzgr.Ptr.40 990 m/s (3,200 ft/s) 143 120 97 77


Penetration figures (90 degrees) uses American and British 50% success criteria,
and allowing direct comparison to foreign gun performance.[3]
Gun type Ammunition type Muzzle velocity
(m/s)		 Penetration (mm)
100 m 250 m 500 m 750 m 1000 m 1250 m 1500 m 2000 m 2500 m 3000 m
7.5 cm StuK 40 L/43 APCBC 740 m/s (2,400 ft/s) 133 128 121 114 107 101 95 85 75 67
7.5 cm StuK 40 L/43 APCR 920 m/s (3,000 ft/s) 173 164 151 139 127 117 108 91 77 65
7.5 cm KwK 40 L/48 APCBC 750 m/s (2,500 ft/s) 135 130 123 116 109 103 97 86 76 68
7.5 cm KwK 40 L/48 APCR 930 m/s (3,100 ft/s) 176 167 154 141 130 119 109 92 78 66

Usage of KwK or PaK/StuK variant

L/43

L/48


See also

Weapons of comparable role, performance and era

References

  1. ↑ http://www.quarryhs.co.uk/ammotable8.htm
  2. ↑ Sturmgeschutz & Its Variants, Walter J. Spielberger, P67, ISBN 0-88740-398-0
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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